Unlocked Sprint Galaxy S4 won’t detect SIM card, other issues

Sprint Galaxy S4

We give you another post that answers some questions sent to us by our readers about their #GalaxyS4. If you want to look for more Galaxy S4 troubleshooting, don’t forget to visit this page.

  1. Galaxy S4 won’t turn on/black screen issue
  2. Galaxy S4 call dialing not working properly
  3. Galaxy S4 display problem after screen was replaced
  4. Unlocked Sprint Galaxy S4 won’t detect SIM card
  5. Galaxy S4 power button not working
  6. Galaxy S4 screen darker than usual

If you are looking for solutions to your own #Android issue, you can contact us by using the link provided at the bottom of this page, or you can install our free app from Google Play Store.


Problem #1: Galaxy S4 won’t turn on/black screen issue

I bought an S4 (Sprint locked) about month ago from eBay. I activated the phone with Freedompop. It was fine until yesterday. 2 days ago, I saw the notice of “System Update” so I installed it. Actually I was not sure if it is Update of Android system or firmware update. It was fine at that moment and then it started to update some apps automatically.

However, yesterday morning (Sat) S4 was blacked out, and it could not be turned on. I plugged it to the wall charger, but it showed 50% battery left, then vibrated and turned on itself, showing Samsung logo and Sprint logo, but it blacked out before showing the screen lock interface. Then it started again. I pulled the battery, then when I put battery back. It vibrated. Sometimes it was turned on showing logo, sometimes not, but most of the time blacked out before showing PIN for “screen lock”.

I tried Recovery. It never succeeded because the phone was blacked out before I could reach anything. When I pressed 3 keys, sometimes no response at all. I guess the phone was in the mode “power on”, but just showing blackout.

Please suggest if the battery has issues or Cache issues, or anything else. Thanks. — Sheen

Solution: Hi Sheen. At this point, we really can’t say for sure what might the cause of the problem be. An issue like this can be caused by software or hardware malfunction. It’s good to check first though if a software glitch may be the reason for the trouble. If you can’t boot your S4 in recovery mode, consider restarting it in download mode (Volume Down, Power, and Home buttons simultaneously). If the phone will only boot in download mode, also called Odin mode, then the most likely reason for the problem may be firmware corruption. You have to try flashing the stock ROM for your phone in order to bring it back online again. If you don’t have any idea how to do this, simply search Google for online resources.

You can also try to restart the phone in safe mode to see if it boots that way. While safe mode is most useful if you suspect that a third party app is messing up with the system, it still is a good way to see if your device responds to button combination command. Simply follow these steps on how to boot your phone in safe mode:

  • Turn the device off completely.
  • Press and hold the Power button.
  • Once the Samsung Galaxy S4 logo appears on the screen, release the Power button.
  • As soon as you release the Power button, press and hold the Volume Down key.
  • Continue holding the Volume Down key until the phone has completed the reboot process.
  • If you can read ‘Safe Mode’ at the bottom left corner of the screen, release the Volume Down key.  Otherwise, repeat the process until you can boot the phone to Safe Mode.

If your phone won’t respond to any button combination, that’s a clear indication that there’s a hardware problem behind. Hardware  trouble can range from simple power button failure to other components not working inside. Kindly bring the phone to your local repair shop for diagnostics.

Problem #2: Galaxy S4 call dialing not working properly

Just got phone brand new from Amazon. Did Internet search for business. Google results appear and a phone handset symbol appears next to business’ phone #. Touch the symbol to call the number. Phone then switches to screen to show its dialing a number. However it never actually makes the call,  just says “dialing” and goes on until I hit end call button. No ringing sounds or evidence that call is going through. Then when I touch the end call button the phone stays on the screen showing it’s attempting to make the call. I can exit that screen and do other things on the phone but if i go back to make a phone call I can’t make any calls out because the phone is still stuck on trying to call the number;  it just won’t end or close out. I have to restart phone in order to be able to make phone call by dialing number or choosing from contact list. This happens with any number I try to call by finding it online and pressing the call symbol next to # on the Google search. — Kari

Solution: Hi Kari. This must be a cache issue for the Contacts app or dialing app you’re using. Try to delete the cache and data of the said app to see the difference. Make sure that you create a backup of your contacts list before doing the procedure as it will wipe all app data.

  • Go to Settings.
  • Proceed to Applications.
  • Select Manage Applications.
  • Tap the All tab.
  • Choose the name of the app involved by tapping it.
  • From there, you will see the Clear Cache and Clear Data buttons.

You can also try refreshing the phone’s system cache by doing the steps below:

  •  Turn off the Galaxy S4 completely.
  • Press and hold the Volume Up and the Home keys together, then press and hold the Power key.
  • When the S4 vibrates, release both the Home and Power keys but continue holding the Volume Up key.
  • When the Android System Recovery shows on the screen, release the Volume Up key.
  • Using the Volume Down key, highlight the option ‘wipe cache partition’ and press the Power key to select it.
  • When the wiping of the cache partition is finished, highlight ‘Reboot system now’ and hit the power key.

Problem #3: Galaxy S4 display problem after screen was replaced

I broke my phone’s screen about 2 weeks ago, and I did what anyone in my situation would do. I bought a new screen to replace the old one. The screen i got came built into the mid-frame, so all i had to do was move over some components. When i finished, the device powered on and was functional, but whenever i apply pressure to any point at the top of the device, specifically the two top corners of the screen, the screen turns green with a lot of horizontal lines. Sometimes the screen will go totally black and only flash a little bit of green in the middle when i activate the screen. I’m not sure f that made any sense, but if it did, do you think it was because i assembled it poorly, or because i bought faulty hardware? — Corey

Solution: Hi Corey. If you got the screen replacement part from a good source, chances are the problem right now stems from the way you did the procedure. The display assembly is composed of three major parts — the digitizer, the LCD, and digitizer flex cable. We don’t know which of these three you replaced but plucking one out from the system can sometimes be tricky. The same can be said during the replacement process of the specific part. Try to re-do your steps to check if there’s a loosely connected component somewhere. We’re afraid this is the only way to determine if the trouble is due to bad component, or improper assembly.

Problem #4: Unlocked Sprint Galaxy S4 won’t detect SIM card

I gave my phone to someone to unlock it from Sprint for me. I got it back from him and he advised me to download Samsung Kies and do a final update through it. I did that and when I place the SIM card from my family mobile phone into it, it says invalid SIM and it says “System Update” on the notification bar on the top. I go to update system and it says it is up to date. What do I need to do to finish up this process of getting the device to accept my family mobile SIM?

BTW, I’m not going through Sprint to have them unlock it because they say I owe them $800. I could buy a new phone for that. Also, when I select UICC unlock, update profile, and update PRL, it says “initializing application”, that disappears and nothing ever happens. — Julian

Solution: Hi Julian. If you have the phone unlocked via third party, you must go back to them for assistance regarding this problem. Either the phone is not truly unlocked, or they did not do it properly.

There are two ways to unlock phones. One is by asking your carrier (in your case Sprint) to give you the unlock code, and the other is by getting help from a third party. The first option is obviously out of question as you’re not willing to pay your remaining balance with Sprint. Now, the problem is that your phone won’t detect your SIM card. This means that either the phone has not been unlocked, or that your device is not simply unable to connect with the towers of your new service provider. Unlocking a phone does not change its hardware and won’t actually help if your device is designed to work with a certain band frequency only. Wireless carriers use assigned frequency in order to provide service. For example, we know that Sprint operates a nationwide CDMA network in the 1900 MHz PCS band together with other specific bands. Your S4 was specifically designed to work within these frequency ranges. Unlocking it doesn’t mean it can now connect to, say, Verizon’s 850 MHz or 700 MHz Block C frequency bands.

Either that or the unlocking process was amiss in the first place. Make sure you ask assistance from the party that unlocked the phone to shed more light on the matter.

Problem #5: Galaxy S4 power button not working

When I clicked the power button to turn off the screen as I normally do, and have for the past year that I’ve had the phone for, instead of simply turning off the screen, it completely shut down the phone, and was non-responsive to holding down the power button for at least half an hour. It was charging for that half an hour, because I had thought that the battery had overheated and that my phone had just died. However, this was not the case.

Eventually, my phone responded to my attempts to turn it back on, and all was well, until I hit the power button again, and the phone shut down for another half hour, despite the numerous times I attempted to turn it back on. When it finally turned back on again, I just figured I should avoid using the power button, but later, out of habit, I clicked it again. This time, the phone has been non-responsive for over 2 hours so far. I’ve tried taking out the battery, holding the power button for a minute, and then putting the battery in.

When I do this, it vibrates and the Samsung logo comes up, but then the screen goes black again and is non-responsive. I then tried charging it for ten minutes before attempting to turn it back on, and it remained non-responsive. Please help. — Kaylee

Solution: Hi Kaylee. Your phone’s power button may have been damaged. This is the oft-used button compared to the other ones and it’s prone to malfunction after years of usage. Kindly have the phone checked so you can have that button replaced if needed.

Problem #6: Galaxy S4 screen darker than usual

Hi. I was wondering what I should do with my screen. I have a Samsung Galaxy S4 Active. I don’t know what happened but suddenly my screen went black with white stripes and I took the battery out and wait some minutes, then when I put it back on it didn’t work for about 3 hours. After that the cellphone worked normally but I notice that the Facebook bar is there even if I am not on Facebook and also the edges of the screen are darker than usual.

What should i do? Is it something that I can do myself or Do i have to take my cell phone somewhere to be checked?

Please, I really do hope you can help me. (Sorry about my english). — Valery

Solution: Hi Valery. If you can see a persistent discoloration or abnormal color on the screen, that’s indicative of display problem. Like Kaylee above, we suggest that you the device checked by your local repair shop so they can replace the display assembly if necessary. As much as would like to help you, there’s just nothing that we can do about a hardware problem like the one you have here.




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